I'm thinking of getting a Zire 31 instead of a 21 for the better screen features, but the review of the 31 says the battery is not user replaceable. Does this mean what it seems to mean? That is, that once the battery runs out, you need to get a new PDA? If so, what's typical battery life? If not, what does it mean?

u r right. its not like a cell phone battery that can be changed. its an internal one. the average life of palm batteries is about 2 years. after that the palm is as good as dead. my advice to you will be to not buy the zire 31...the screen looks baddd...and its not a reliable unit. buy a zire 72 instead (but you'll have to live with the paint peeling problem)